JP2011133217A - Heat transfer pipe and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat transfer characteristics of a heat transfer pipe and to provide a method of manufacturing the heat transfer pipe. <P>SOLUTION: This invention relates to the heat transfer pipe including a pipe axis, a pipe wall, a pipe outer face and a pipe inner face. Inner fins continuously extending from the pipe wall and extending axially in parallel or circulating spirally are formed on the pipe inner face, and each inner fin includes two fin lateral faces and one fin tip. A continuously extending groove is formed between the adjacent inner fins. The fin tip includes at regular intervals recurring elevations having a substantially truncated pyramidal shape. In the solution, the fin lateral faces of the inner fin are raised in the radial direction along the contour line defined by a transitional edge from one fin lateral face to the fin tip since projections continued from the fin lateral face are formed in this region. In addition, this invention relates to the method of manufacturing the heat transfer pipe. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat exchanger tube according to the preamble of claim 1 and a method of manufacturing the heat exchanger tube according to the preamble of claim 8 or claim 9.

  Heat transfer takes place in many areas of refrigeration and air conditioning technology as well as process technology and energy technology. In these fields, tubular heat exchangers are often used for heat transfer. In this case, in many applications, a liquid or gaseous medium flows on the inner surface of the tube, and the liquid or gaseous medium is cooled or heated depending on the direction of the heat flow. Heat is released or extracted from the media inside the tube.

  In order to be able to transfer heat between the heat-releasing medium and the heat-absorbing medium, the temperature of the heat-releasing medium must be higher than the temperature of the heat-absorbing medium. This temperature difference is called a driving temperature difference. The greater the drive temperature difference, the more heat transfer. On the other hand, efforts may be made to keep the drive temperature difference small. This is because there is an advantage to process efficiency.

  It is known that heat transfer can be enhanced by structuring the heat transfer surface. As a result, it is possible to transfer more heat per unit area of the heat transfer surface than in the case of a smooth surface. Furthermore, the process can be configured more efficiently by reducing the driving temperature difference. In the case of metal heat exchanger tubes, the heat transfer surface is often structured by forming fins or similar elements from the tube wall material. These integrally molded fins have a solid metal bond with the tube wall, and thus can transfer heat optimally.

  A frequently used heat exchanger is a tube bundle heat exchanger. In this apparatus, a tube having a structured inner surface and outer surface is often used. A heat exchanger tube structured for a tube bundle heat exchanger typically has at least one structured region, a smooth end member, and possibly a smooth intermediate member. The smooth end member or intermediate member defines a structured area. In order to be able to attach the tube to the tube bundle heat exchanger without hindrance, the outer diameter of the structured area should not be larger than the outer diameter of the smooth end member and intermediate member.

  On the inner surface of the tube, axially parallel fins or helical fins may be used to improve heat transfer characteristics. Adding the fins increases the internal surface area of the tube. Furthermore, if the fins are arranged in a spiral, the turbulence of the medium flowing in the tube is increased, thus improving heat transfer. It is known that by providing the inner fin with a notch or groove, the heat transfer characteristics of an axially parallel fin or a helical fin attached to the inner surface of the tube can be improved. Examples thereof can be found in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6. By notching the fins, a structure with alternating fin heights and lateral material protrusions is created on the fin sides. This structure assists in increasing the disturbance of the medium flowing in the tube.

  In particular, in the application examples of the refrigeration technology and the air conditioning technology, the efficiency of the refrigeration apparatus at the time of partial load has become increasingly significant. Since the speed of the medium flowing in the pipe is significantly reduced at the time of partial load, the through-flow rate of the heat transfer medium may be reduced. At this time, since most of the heat transfer resistance is transferred to the inner surface of the pipe, it is necessary to further improve the structure of the inner surface of the pipe known today, particularly for a low flow rate.

European Patent No. 1312885B1 China Patent Application Publication No. 101556124A Specification China Patent Application Publication No. 101556125A Specification US Pat. No. 5,992,513 US Pat. No. 6,018,963 US Pat. No. 6,412,549

  An object of the present invention is to improve a heat transfer tube with respect to heat transfer characteristics and to provide a method for manufacturing this type of heat transfer tube.

  The features of the present invention are represented by the structure of claim 1 with respect to the heat exchanger tube. Furthermore, with respect to the method of manufacturing the heat exchanger tube, the features of the present invention are represented by claims 8 and 9. Other dependent claims relate to other advantageous configurations of the invention.

  The present invention relates to a heat exchanger tube having a tube axis, a tube wall, a tube outer surface, and a tube inner surface. Inner fins are formed on the inner surface of the tube so as to extend continuously from the tube wall and extend in parallel with the axis or spirally. Each inner fin has two fin side surfaces and one fin tip. A continuously extending groove is formed between the adjacent inner fins. The fin tip has a ridge that repeats at regular intervals, and the ridge has a substantially truncated pyramid shape. According to the solution according to the present invention, a projecting portion connected from the fin side surface portion is formed in this region along the contour defined by the transition edge from one fin side surface portion to the fin tip portion. Accordingly, the fin side surface portion of the inner fin is raised in the radial direction of the tube.

  In this case, in order to improve the heat transfer on the inner surface of the tube, the present invention increases the disturbance of the medium flowing in the tube and disturbs the flaky boundary layer formed in the medium near the wall. Departure. For this purpose, specially shaped structural elements are used on the inner surface of the tube, for example with axially parallel inner fins or additional inner fins that spiral around. Such a feature is a raised portion having a substantially truncated pyramid shape provided at the tip of the fin. The truncated pyramid-shaped raised portion provided at the fin tip includes, for example, all shapes (for example, bar-like shapes) extended in the spatial direction. The side surface of the truncated pyramid may be formed as a curved side surface or a cover surface. The ridges are repeated at regular intervals in the fin extending direction. The inner fin has a maximum fin height H2 in the region of the raised portion. The area of the fin tip between the two ridges is a relative recess. The inner fin then has a minimum fin height H3. Each fin height is measured from the tube wall. The transition from one ridge to the next recess is made by the inclined side of the truncated pyramidal ridge. The side surface of one of the truncated pyramidal ridges extending parallel to the fin side surface portion forms a seamless transition with the fin side surface portion.

  As the flow rate of the medium decreases, the flaky boundary layer increases accordingly. When the thickness of the flaky boundary layer is approximately the same as the maximum fin height, the turbulence increasing action of the internal structure is significantly reduced. It has been found that this undesirable action can be prevented by providing a protrusion at the fin tip of the inner fin. The protrusion extends toward the fin tip at the transition edge of one fin side. This is because the transition region is slightly raised in the radial direction. As a result, the fin tip has an outstanding microstructure starting from the fin side surface. In other words, the typical appearance of the protrusion is an ear-shaped shape where a significant number of sides of the truncated pyramidal ridge slightly distorts the classical geometry of the truncated pyramid. Are formed in the radial direction. The projections according to the invention advantageously stand out in the inclined pyramid side of the ridge, whereas these projections are less prominent in the area between the ridge cover surface and the two ridges. .

  On the other hand, by providing a notch in the initially set inner fin to produce a structure with a state-of-the-art setting known from US Pat. No. 5,992,513, the side surface of the inner fin in the region of the notch The lateral material protrusions are formed on the surface. These material protrusions are provided at different heights on the fin side surface according to the depth of the notch. However, the distance to the wall is always smaller than the maximum height of the fin. These lateral material projections cause auxiliary turbulence in the flow as long as the flaky boundary layer is thinner than the spacing from the tube wall. As the flow velocity decreases and the viscosity of the medium increases, the flake-like boundary layer becomes thicker and the action of the lateral material projections is significantly reduced. In addition, in this case, an area may be formed between the material projection and the tube wall so as to almost stop the flow and thus the heat transfer.

  A particular advantage of the solution according to the invention is that the microstructure of the protrusions in the region of the fin tip creates additional vortices and thus increases the turbulence of the medium flowing in the tube. The resulting increase in efficiency is particularly noticeable when the flow rate is low. This is because the protrusions prevent the formation of flaky boundary layers. Thus, the protrusions significantly enhance the heat transfer compared to the structure known from the state of the art that does not have these protrusions in the radial direction.

  In an advantageous configuration of the invention, at least one of the side portions of one truncated pyramidal ridge may be formed in a concave shape. These side portions have curved portions directed into the inside of the pyramid, and these curved portions form an edge structure or a sharper edge structure that protrudes prominently on the side portions of the truncated cone. Such a sharp-edged structure prevents laminar flow and additionally promotes vortex formation and increases heat transfer efficiency.

  Advantageously, the truncated pyramidal ridges may be formed asymmetrically. Thus, in order to further optimize the heat transfer characteristics, the asymmetry may be correspondingly adapted to the flow behavior inside the tube. For example, the pyramid edges that most often prevent laminar flow may be correspondingly sharpened.

  In a preferred embodiment of the invention, the frustoconical ridge projects from the recess between the two ridges by 20% to 100% of the height of the inner fin at the location of the recess. .

  If the protuberance protrudes from the recess by no more than 20% of the minimum inner fin height H3, the radial protrusion is not so prominent that it can significantly affect the flow. Protrusion that protrudes from the recess by 100% or more of the minimum inner fin height H3 is difficult to manufacture. As a result, there is a problem that the tool is subjected to an undesired load and its life is shortened. For tubes with an inner diameter between 10 mm and 25 mm, the minimum height H3 of the inner fin is preferably 0.20 mm to 0.45 mm and the maximum height H2 of the inner fin is preferably 0.35 mm to 0.60 mm. is there. In this case, the ridge at the tip of the fin typically protrudes from 0.05 mm to 0.20 mm from the recess between the two ridges.

  Advantageously, the angle of inclination α of the ridge is at most 120 °. The inclination angle α is an angle formed by the inclined side surface portion of the truncated pyramid-shaped protruding portion with the fin tip portion. If this angle is 120 ° or more, the raised portion at the tip of the fin forms a corrugated structure and does not sufficiently affect the flow of the medium.

  In an advantageous configuration, an external structure is formed on the outer surface of the tube. Accordingly, the heat exchanger tube according to the present invention has a structured portion on its outer surface that enhances heat transfer on the tube outer surface. Advantageously, the external structure is formed in the form of an integral outer fin extending around the screw. Monolith refers to a type of fin that is machined from the tube wall in the molding process. Outer fins increase the outer surface of the tube, which enhances heat transfer.

  Another aspect of the present invention relates to a first method for manufacturing a heat exchanger tube according to the present invention, in which the following method steps are carried out:

  a. In a first forming region, a method step of radially forming a wall of a smooth tube with a first spinning tool that circulates on the outer surface of the smooth tube;

  b. In the first forming region, the tube wall is a first rolling mandrel located in the tube, which is rotatably supported and has an axially parallel or spiral groove of depth T1 on the outer surface of the mandrel. Supporting the first rolling mandrel, wherein the inner wall is formed by pushing the material of the tube wall into the groove of the first rolling mandrel;

  c. In the second forming region, a method step of radially forming the wall of the smooth tube with a second spinning tool that circulates on the outer surface of the smooth tube;

d. In the second forming region, the tube wall is a second rolling mandrel located in the tube, which is likewise rotatably supported and has an axis parallel or spiral groove of depth T2 on the outer surface of the mandrel By pressing the material of the tube wall and the material of the internal structure formed in the first forming region into the groove of the second rolling mandrel, with the second rolling mandrel having A continuously extending axially parallel inner fin or spiral inner fin is newly formed, where the inner fin formed in the second forming region is significantly stronger than the inner structure formed in the first forming region. A method step of forming a ridge at the tip of the inner fin from the material that is prominent and pushed into the groove of the first rolling mandrel in the first forming region;
And the tensioning device ensures the axial conveyance of the tube passing through the forming region.

  The present invention uses, in the first method, an apparatus comprising at least two spinning tools spaced apart from each other, arranged on the outer surface of the tube, for producing a heat exchanger tube according to the invention. Is assumed. The spinning tool consists of a plurality of balls or rollers which are positioned in a ring at the receiving part and are rotatably supported. The receptacle with the ball or roller is housed in a stationary device and can rotate around the tube, which can cause the tube wall to deform radially. In addition, a separate tensioning device is provided, which can be used to pull the tube axially through the spinning tool.

  To machine the tube, the spinning tool is rotated around the tube and the tube is pulled axially by a tensioning device. In the working area of the spinning tool, the tube wall is supported by a deformed rolling mandrel.

  Another aspect of the invention relates to a second method for manufacturing a heat exchanger tube according to the invention, in which the following method steps are carried out:

  a. The fin material is obtained by removing material from the tube wall by the first rolling step, the resulting finned tube is rotated by the rolling force, and the finned tube is moved forward in response to the resulting threaded outer fin. A method step of forming an outer fin extending in a threaded manner on the outer surface of the smooth tube in the first forming region by extruding to the outer surface, wherein the outer fin is formed from an unshaped smooth tube while increasing its height. When,

  b. In the first forming region, the tube wall is a first rolling mandrel located in the tube, which is rotatably supported and has an axially parallel or spiral groove of depth T1 on the outer surface of the mandrel. Supporting the first rolling mandrel, wherein the inner wall is formed by pushing the material of the tube wall into the groove of the first rolling mandrel;

  c. In the second rolling step, a method step of forming outer fins in a second forming region that is located at a distance from the first forming region and that is further raised in height;

d. In the second forming region, the tube wall is a second rolling mandrel located in the tube, which is likewise rotatably supported and has an axis parallel or spiral groove of depth T2 on the outer surface of the mandrel By pressing the material of the tube wall and the material of the internal structure formed in the first rolling step into the grooves of the second rolling mandrel, with the second rolling mandrel having A continuously extending axially parallel inner fin or spiral inner fin is newly formed, in which case the inner fin formed in the second forming region is significantly stronger than the inner structure formed in the first forming region. A method step of forming a ridge at the tip of the inner fin from the material that is prominent and pushed into the groove of the first rolling mandrel in the first forming region;
To implement.

  In the second method, the present invention consists of n = 3 or 4 tool holders for producing the heat exchanger tube according to the present invention, and at least these tool holders are arranged at intervals from each other. It is assumed that an apparatus incorporating two rolling tools is used. The axis of each tool holder extends with an inclination with respect to the tube axis. The tool holders are each arranged around the tube with a shift of 360 ° / n. The tool holder can be fed in the radial direction. The tool holder is arranged in a stationary rolling mill. The rolling tool is composed of a plurality of rolling disks arranged in parallel to each other, and the diameter of the rolling disk increases in the direction of the forward forming rate of the outer fins.

  To machine the tube, a rolling tool arranged around and rotating is fed radially to the smooth tube and engaged with the smooth tube. This causes the smooth tube to rotate about its axis. Since the axis of the rolling tool is inclined with respect to the tube axis, the rolling tool forms an outer fin extending around the threaded wire from the wall of the smooth tube, and at the same time, the threaded wire The generated finned tube is pushed forward according to the pitch of the outer fins extending so as to go around. The first rolling tool in each tool holder begins forming the outer fins, and the other rolling tools in each tool holder continue to further form the outer fins. The spacing between the two rolling tools needs to be aligned so that the rolling disk of the next rolling tool engages in a groove between the outer fins formed by the previous tool.

  The distance between the centers of two adjacent outer fins measured along the tube axis is called the fin pitch p. The fin pitch is usually between 0.4 mm and 2.2 mm. The outer fins preferably extend around like a multiple thread. In the working area of the rolling tool, the tube wall is supported by a deformed rolling mandrel.

  Next, a method aspect common to the first and second methods will be further described. Therefore, the constituent members of both apparatuses are two rolling mandrels having different profiles. These rolling mandrels are mounted on a bar in series and coaxially with each other, and are rotatably supported by the bar. The common axis of these rolling mandrels is identical to the axis of the bar and coincides with the tube axis.

  In the first method, the bar is fixed by a suitable holding device so that the rolling mandrel is positioned in the working area of the spinning tool. In the second method, the bar is fixed to the rolling mill itself at the other end. With this bar, the rolling mandrel is positioned in the working area of the rolling tool. In this case, the first rolling mandrel in the forward forming rate direction is positioned in the working area of the first spinning tool or rolling tool in the forward forming rate direction, while the second rolling mandrel in the forward forming rate direction is positioned in the forward forming rate direction. Is positioned in the work area of the next spinning or rolling tool. The outer diameter of the second rolling mandrel is somewhat smaller than the outer diameter of the first rolling mandrel.

  The profile of the rolling mandrel usually consists of a plurality of substantially trapezoidal grooves, which are arranged on the outer surface of the rolling mandrel parallel to each other. The inclination angle of the groove of the first rolling mandrel is denoted as β1. The groove of the first rolling mandrel extends at a twist angle of 0 ° to 60 ° with respect to the axis of the rolling mandrel and has a depth T1. The inclination angle of the groove of the second rolling mandrel is denoted as β2. The groove of the second rolling mandrel extends with a twist angle of 0 ° to 45 °, preferably 25 ° to 45 ° with respect to the axis of this rolling mandrel, and has a depth T2. The groove depth T2 of the second rolling mandrel is significantly greater than the groove depth T1 of the first rolling mandrel. The twist angle of the rolling mandrel is selected to produce an intermediate angle of at least 40 °. The intermediate angle is preferably between 70 ° and 100 °. In order to achieve the desired intermediate angle, preferably the grooves of the first rolling mandrel are in the opposite direction to the grooves of the second rolling mandrel.

  In the first forming region, the radial force of the first spinning tool or first rolling tool forces the tube wall material into the groove of the first rolling mandrel. This forms an internal structure in the form of an axially parallel inner fin or helical inner fin on the inner surface of the tube. The twist angle of the inner fin measured with respect to the tube axis is equal to the twist angle of the groove of the first rolling mandrel. The height H1, measured from the tube wall, of the inner fin formed in this first forming step is preferably between 0.05 mm and 0.20 mm. Therefore, the distinction of this internal structure is relatively weak. The height H1 of the inner fin formed in the first forming step is approximately the same as the groove depth T1 of the initial rolling mandrel, but not greater. Suitably, the first rolling mandrel grooves should be completely filled with material. In this case, the height H1 of the inner fin formed in the first forming step is the same size as the groove depth T1 of the first rolling mandrel.

  The outer diameter of the second rolling mandrel must be smaller than the inner diameter of the inner diameter of the tube after forming the first inner fin. The inner diameter of the tube after forming the first inner fin is approximately equal to the outer diameter of the first rolling mandrel minus two times the height H1 of the inner structure formed in the first rolling step.

  In the second forming region, the radial force of the other spinning tool or rolling tool causes the tube wall material and the inner fin material formed in the first forming region to move into the groove of the second rolling mandrel. Push into. As a result, continuously extending inner parallel fins or spiral inner fins are newly formed on the inner surface of the tube. The twist angle measured with respect to the tube axis of this newly formed inner fin is equal to the twist angle of the groove of the second rolling mandrel. Since the twist angle of both rolling mandrels is selected to form an angle of at least 40 °, the inner fin material formed in the first forming step is a rule set by the profile of the second rolling mandrel. It is deformed again at regular intervals. A portion of this deformed material forms a radial protrusion according to the present invention at the tip of the inner fin formed in the second molding step. A region of the inner fin formed in the first rolling step that has not been deformed by the second forming slip forms a truncated pyramidal ridge at the tip of the inner fin formed in the second rolling step. To do. This manufacturing method makes it possible to make the radial protrusions according to the invention particularly stand out on the inclined side of the truncated pyramidal ridge, while the protrusions are on the tip of the ridge and on the two ridges. Less noticeable in the area between.

  To allow the desired shaping of the new inner fin from the tube wall material in the second shaping step, the groove depth T2 of the second rolling mandrel is determined by the inner fin formed in the first shaping step. It must be significantly greater than the height H1. Thereby, it becomes possible to make the inner fin formed in the second molding step stand out more strongly than the internal structure of the first molding step. The groove depth T2 of the second rolling mandrel must be at least as large as the target maximum height H2 of the new inner fin. Depending on the quantity and height of the inner fins, the inner surface area of the finished tube can exceed the inner surface area of the non-formed smooth tube by 100% or less.

  In an advantageous configuration of the invention, the internal structure formed in the first forming region causes the internal surface area of the tube with the internal structure to be at least 4% and at most 30% compared to the internal surface area of the non-formed smooth tube. Can only be enlarged. Therefore, the distinction of this internal structure is relatively weak.

  In another advantageous configuration of the invention, the groove depth T2 of the second rolling mandrel is at least 2.5 times greater than the groove depth T1 of the first rolling mandrel. This allows the inner fin formed in the second rolling step to reach a maximum fin height H2 that is significantly greater than the height H1 of the internal structure of the first rolling step.

  In an advantageous configuration of the invention, the groove inclination angle (opening angle) of the first rolling mandrel is at most 120 °. Thereby, the advantageous structure of the raised part of the truncated pyramid shape of a fin front-end | tip part can be achieved. And the heat exchanger tube for solving a subject can be obtained.

It is the perspective view which emphasized the shadow in gray of the pipe | tube internal structure provided with the fin and the truncated pyramid-shaped protruding part. It is a perspective view of the pipe | tube internal structure of FIG. It is a detailed view of a truncated pyramidal ridge at the fin tip. It is the perspective view which emphasized the shadow in gray of the pipe | tube internal structure provided with the fin and the asymmetrical truncated pyramid-shaped protruding part. It is a perspective view of the asymmetric pipe | tube internal structure of FIG. It is detail drawing of the asymmetrical truncated pyramid-shaped protruding part of a fin front-end | tip part. It is a figure of the apparatus for manufacturing the heat exchanger tube which attached the fin to the outer surface using an inner mandrel. It is a perspective view of the apparatus for manufacturing the heat exchanger tube which attached the fin to the outer surface using an outer rolling tool and an inner mandrel. FIG. 5 is a graph compared to the general state of the art for improving internal heat transfer by means of the solution according to the invention.

  Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  In all the drawings, the members corresponding to each other are given the same reference numerals.

  FIG. 1 is a perspective view of the structure of the tube inner surface 22 of the heat transfer tube 1 having the inner fins 3 and the truncated pyramid-shaped ridges 34 with gray shades emphasized. FIG. 2 is a perspective view of the tube internal structure of FIG.

  Inner fins 3 are formed on the inner surface 22 of the tube so as to continuously circulate in a spiral shape. In this case, each inner fin 3 has two fin side portions 31 and one fin tip portion 32. ing. A groove 33 extending continuously is formed between the inner fins 3 adjacent to each other. The fin tips 32 have ridges 34 that repeat at regular intervals, and these ridges 34 have a substantially truncated pyramid shape (in the example, a planar weight). The fin side surface portion 31 of the inner fin 3 swells along a contour defined by a transition edge from one fin side surface portion 31 to the fin tip portion 32. FIG. 3 is a detailed view of the truncated pyramidal ridge 34 provided at the fin tip 32, and the ridge 34 is formed in this region so as to protrude from the fin side surface 31 along the contour line. A portion 37 is provided in the radial direction.

  In FIG. 3, the two side surface portions 36 of the illustrated truncated pyramid-shaped raised portion 34 are formed in a concave shape. These side portions 36 are also part of the fin tip portion 32 and have a curved portion directed toward the inside of the pyramid portion. The curved portion allows the edge structure or A sharp edge structure is formed in the shape of the projection 37 in the radial direction. The fin tip 32 is formed in the shape of a recess 35 between the raised portions 34. The sharp edge structure acts to promote vortex formation to improve heat transfer characteristics.

  4 to 6 are perspective views in which the structure of the tube inner surface 22 of the heat exchanger tube 1 including the inner fins 3 and the truncated pyramid-shaped raised portions 34 is gray and the shadow is emphasized. FIG. 5 is a perspective view of the tube internal structure of FIG. In FIG. 4 to FIG. 6, the truncated pyramidal ridges 34 are formed asymmetrically with respect to the longitudinal section of the inner fin 3.

  Also in FIG. 6, the two side surfaces 36 of the truncated pyramid-shaped raised portion 34 shown in the figure are formed in a concave shape. These side portions 36 are also part of the fin tip portion 32 and have a curved portion directed toward the inside of the pyramid portion. The curved portion allows the edge structure or A sharp edge structure is formed in the shape of the projection 37 in the radial direction. Due to the asymmetry, a sharp edge structure correspondingly adapted to the flow conditions inside the tube is created by the radial protrusions 37 to promote vortex formation.

  FIG. 7 is a diagram of an apparatus for manufacturing the heat exchanger tube 1 in which fins are formed on the outer surface using the two rolling mandrels 100 and 200. FIG. 8 is a perspective view of an apparatus for manufacturing the heat exchanger tube 1 in which fins are formed on the outer surface using the outer rolling tool and the inner mandrel corresponding to FIG. 7. In the manufacturing method of the heat exchanger tube 1 according to the present invention, the fin material is obtained by removing the material from the tube wall 2 by using the rolling tool 300 constituted by the rolled disc 301 in the first rolling step. Thus, the outer fins 4 extending in a thread form are formed in the first forming region on the outer surface of the smooth tube 10. The finned tube thus produced is rotated by a rolling force, and the produced threaded outer fin 4 is pushed forward. The tube wall 2 is supported by a first rolling mandrel 100 in the tube in the first forming region. The first rolling mandrel 100 is rotatably supported and has an axially parallel groove or a spiral groove having a depth T1 on the outer surface 101 of the mandrel. In this case, the material of the tube wall 2 is used as the first rolling mandrel 100. By pushing into the groove of the rolling mandrel 100, an internal structure that is relatively weak is formed.

  In the second rolling step, the outer fins 4 are formed on the pipe outer surface 21 in the second forming region which is located at a distance from the first forming region and is further increased in height, and this second forming region The tube wall 2 is supported by a second rolling mandrel 200 that is also rotatably supported in the tube and has a helical groove with a depth T2 on its mandrel outer surface 201. At that time, the material of the tube wall 2 and the material of the internal structure formed in the first rolling step are pushed into the groove of the second rolling mandrel 200, so that the continuously extending inner fins 3 are connected to the inner surface of the tube. 22 is newly formed. The inner fin formed in the second molding region stands out considerably stronger than the internal structure formed in the first molding region. The raised portion 34 at the tip of the inner fin 3 is formed from a material that is pushed into the groove of the first rolling mandrel 100 in the first forming region.

  FIG. 9 is a graph illustrating the functional effect of the internal structure according to the present invention. Taking a tube with an inner diameter of 16 mm as an example, the improvement rate of internal heat transfer to the smooth tube is shown as a function of the speed of water flowing in the tube. The average temperature of water is 9 ° C. The graph shows both the coefficient of performance of the pipe according to the state of the art and the coefficient of performance of the pipe with the internal structure according to the invention. In the comparison tube, a structure according to the set value of the state of the art cited from US Pat. No. 5,992,513 is realized. As can be seen, the internal structure according to the present invention has a significant increase in efficiency for water speeds of 2 m / s or less compared to state-of-the-art tubes. When the water speed is 1 m / s or less, the effect is almost 40%.

DESCRIPTION OF SYMBOLS 1 Heat exchanger tube 2 Tube wall 21 Tube outer surface 22 Tube inner surface 3 Inner fin 31 Fin side surface part 32 Fin tip part 33 Groove 34 Raised part 35 Recessed part 36 Side part of raised part 37 Projection part 4 Outer fin 10 Smooth tube 100 1st Rolling mandrel 101 First mandrel outer surface 200 Second rolling mandrel 201 Second rolling mandrel mandrel outer surface 300 Rolling tool 301 Rolled disc α Tilt angle of raised portion β1 Tilt angle of first rolling mandrel β2 Tilting angle of the groove of the second rolling mandrel T1 Groove depth of the first rolling mandrel T2 Groove depth of the second rolling mandrel A Pipe axis

Claims (12)

A heat exchanger tube (1) comprising a tube axis (A), a tube wall (2), a tube outer surface (21), and a tube inner surface (22),
An inner fin (3) extending continuously from said tube wall (2) and extending parallel to the axis or spirally is formed on said tube inner surface (22);
Each inner fin (3) has two fin sides (31) and one fin tip (32);
A continuously extending groove (33) is formed between the inner fins (3), which are adjacent to each other,
The fin tips (32) have ridges (34) that repeat at regular intervals;
The ridge (34) has a substantially truncated pyramidal shape;
In the heat exchanger tube (1),
A protrusion (37) that continues from the fin side surface (31) in this region along the contour defined by the transition edge from one fin side surface (31) to the fin tip (32). The heat transfer tube (1), wherein the fin side surface portion (31) of the inner fin (3) is raised in the radial direction of the tube by being formed.   Heat exchanger tube (1) according to claim 1, characterized in that at least one of the side portions (36) of one frusto-pyramidal ridge (34) is formed in a concave shape.   The heat exchanger tube (1) according to claim 1 or 2, characterized in that the truncated pyramidal ridge (34) is formed asymmetrically with respect to the longitudinal section of the inner fin (3). ).   The frustoconical ridge (34) extends from the recess (35) between the two ridges (34) to the height of the inner fin (3) at the position of the recess (35). Heat exchanger tube (1) according to any one of claims 1 to 3, characterized in that it projects by% to 100%.   The heat exchanger tube (1) according to any one of claims 1 to 4, characterized in that the angle of inclination α of the raised portion (34) is at most 120 °.   Heat exchanger tube (1) according to any one of claims 1 to 5, characterized in that an external structure (4) is formed on the tube outer surface (21).   Heat transfer according to any one of claims 1 to 6, characterized in that the external structure (4) is formed in the form of an integral outer fin extending around the screw. Instrument tube (1). In the method for manufacturing a heat exchanger tube (1) according to any one of claims 1 to 5, the following method steps are carried out:
a. In a first forming region, a method step of radially forming the wall of the smooth tube (10) with a first spinning tool that circulates on the outer surface of the smooth tube;
b. In the first forming region, the tube wall is a first rolling mandrel (100) located in the tube and is rotatably supported, and is axially parallel to the outer surface (101) of the depth T1. Supported by the first rolling mandrel (100) having a straight groove or a spiral groove, the material of the tube wall being pushed into the groove of the first rolling mandrel (100) A method step for forming an internal structure by:
c. In a second forming region, a method step of radially forming the wall of the smooth tube with a second spinning tool that circulates on the outer surface of the smooth tube;
d. In the second forming region, the tube wall is a second rolling mandrel (200) located in the tube, which is likewise rotatably supported and has an axis of depth T2 on its mandrel outer surface (201). Supported by the second rolling mandrel (200) having parallel or spiral grooves, wherein the material of the tube wall and the material of the internal structure formed in the first forming region are By pressing into the groove of the second rolling mandrel (200), continuously extending axially parallel inner fins or spiral inner fins are newly formed, in this case the second forming region The inner fins formed in step 1 are significantly stronger than the inner structure formed in the first forming region, and are pushed into the grooves of the first rolling mandrel (100) in the first forming region. From I I material, the method step of forming the raised portion (34) at the distal end of the inner fin,
e. A method step of ensuring the axial transport of the tube passing through the forming region by means of a tensioning device;
How to implement. In the method for manufacturing a heat exchanger tube (1) according to claim 6 or 7, the following method steps are carried out:
a. The fin material is obtained by removing material from the tube wall by the first rolling step, the resulting finned tube is rotated by rolling force, and the fin corresponding to the resulting threaded outer fin (4) is obtained. The outer fin (4) extending in a threaded manner is formed on the outer surface of the smooth tube (10) in the first forming region by pushing the attached tube forward, and the outer fin (4) is A method step of forming from a non-formed smooth tube (10) with increasing height;
b. In the first forming region, the tube wall is a first rolling mandrel (100) located in the tube, which is rotatably supported and has an axially parallel groove of depth T1 on the outer surface of the mandrel or The inner structure is supported by the first rolling mandrel (100) having a spiral groove, in which the tube wall material is pushed into the groove of the first rolling mandrel (100). Forming a method step;
c. In the second rolling step, a method step of forming the outer fin (4) in a second forming region that is located at a distance from the first forming region and that is further increased in height.
d. In the second forming region, the tube wall (2) is a second rolling mandrel (200) located in the tube, which is likewise rotatably supported and is deep on the mandrel outer surface (201). Supported by the second rolling mandrel (200) having a groove parallel to the axis of length T2 or a spiral groove, formed by the material of the tube wall (2) and the first rolling step By pushing the material of the internal structure into the groove of the second rolling mandrel (200), continuously extending axially parallel inner fins or spiral inner fins are newly formed. The inner fin formed in the second forming region stands out significantly stronger than the inner structure formed in the first forming region, and the first rolling mandrel (1 From pushed I material into the groove of 0), the method steps of forming a ridge (34) at the distal end of said inner fin (3),
How to implement.   Due to the internal structure formed in the first forming region, the internal surface area of the tube with the internal structure is at least 4% and at most 30% compared to the internal surface area of the non-formed smooth tube (10). 10. A method according to claim 8 or 9, characterized in that it is enlarged.   The depth T2 of the groove of the second rolling mandrel (200) is at least 2.5 times as large as the depth T1 of the groove of the first rolling mandrel (100). The method according to claim 8 or 9.   10. A method according to claim 8 or 9, characterized in that the inclination angle of the groove of the first rolling mandrel (100) is at most 120 [deg.].

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